Stainless hydraulic piping and fittings for newbuilds and ship repair

Newbuild: from piping circuit to commissioning

On newbuild ships, the hydraulic system consists of piping circuits branching out from the power units to deck machinery, hatch covers, ramps and doors, the steering gear and remote-controlled valve systems. When stainless steel pipe is chosen over carbon steel for these lines, the internal pickling and preservation treatments required for carbon steel are largely reduced; weld areas still need cleaning, but external corrosion is no longer a problem throughout the service life.

Points to watch in pipe spool fabrication:

• Matching pipe and components: Outside diameter/NPS, wall thickness (Schedule) and pressure class should be cross-checked together with the elbows, tees, reducers and flanges.
• Welded or removable: Welded joints are used on long straight runs, while a removable point is left at equipment connections by means of a weld nipple or flange.
• Weld quality: Weld bevel preparation, axial alignment and post-weld surface cleaning directly affect sealing; 316L is preferred for parts that will be welded.
• Line cleanliness: Once installation is complete and before commissioning, the lines must be flushed to the target cleanliness level; chips and weld residue are among the main causes of valve and pump failures.

For items that require classification society approval or material certificates, stating this requirement at the quotation stage ensures that the production plan is set up correctly from the start.

Maintenance, repair and drydocking

The list of fittings to be replaced during drydocking often becomes clear only after the ship has entered the dock and the lines have been dismantled. At this point, three approaches save time:

1. Pre-survey: If possible, photos of known faulty lines, port sizes and hose lengths are shared before the ship arrives, and stock items are reserved in advance.
2. Production from samples: Worn, corroded or no-longer-available adapters and special parts are measured from the sample; the thread standard and critical dimensions are confirmed in writing, and production begins after first article approval.
3. Switching from carbon steel to stainless steel: Deck lines that keep rusting are replaced during the overhaul with stainless steel parts of the same size, so the same job does not have to be repeated at the next drydocking.

During an overhaul, the same line may turn out to contain parts from different periods, some BSP and some metric. In such cases, rather than adding a separate conversion adapter at every point, renewing the line to a single standard should be considered; fewer adapters mean fewer potential leak points.

Fast spares for ship crane service teams

Due to chafing, sunlight and salt, the hoses on deck and provision cranes are among the most frequently replaced hydraulic parts on board. Cranes from different manufacturers may combine BSP, JIC/UNF, metric and SAE flange connections. For crane service teams, a hose assembly can be made up using the connection type, length and angle information for both ends of the old hose; supplying frequently used adapters and elbows from stock shortens the time the service team spends waiting on board.

Fitting selection by line type

Information that speeds up your quote request

In shipyard projects, what delays a quotation the most is an incomplete definition. When the following information is shared upfront, stock and manufactured items can be separated in the first round:

• For newbuilds: bill of materials per circuit, pipe outside diameter and wall thickness, flange type and pressure class, working pressure, required delivery sequence.
• For maintenance and repair: a photo of the removed part, its port size or a sample, quantity and the ship's undocking date.
• For crane service: crane manufacturer and model if known, hose end types, angles and lengths.
• In every case: whether class approval, material certificates or testing are expected.

Lead times and supply

Standard sizes in stock are ready to ship within 1-3 business days on average; standard production is scheduled within 5-10 business days on average, hose assemblies made up to length within 5-15 business days on average, and custom-size and project manufacturing within 10-20 business days on average after technical approval. In newbuild projects, splitting the bill of materials into phased deliveries makes it easier to ship in line with the installation sequence. Parts are packed separately by size and order group, with threads and ports closed off by protective caps; when order groups are placed per circuit, packaging follows the same arrangement, so it is easy to tell on site which package belongs to which line.